What does it mean to be human?
For a long time, the answer seemed obvious. Our species, Homo sapiens, with our complex thoughts and deep emotions, were the only true humans to ever walk the Earth. Earlier forms, such as Neanderthals, were thought to be mere steps on a path of evolution, which ended because we were better versions.
This landscape is changing now.
In recent years, researchers have gained the ability to extract DNA from ancient humans, including our early ancestors and other bipedal relatives. Ancient DNA technology has revolutionized the way we study human history It has taken off quickly, with a steady stream of studies exploring human genes for a long time.
Along with more fossils and artifacts, the DNA results suggest a challenging clue: We are not special For most of human history, we shared the planet with them Other types of early humansThese now-extinct groups were very similar to us.
“We can see them as completely human. But what’s interesting is that there’s a different kind of human,” said Chris Stringer, an expert on human evolution at the Natural History Museum in London. “A different way of being human.”
next to, Humans had close, even intimate, interactions with some of these other groups, including Neanderthals, Denisovans, and “ghost groups.” Which we only know through DNA.
“It’s a unique moment in human history when there’s only one of us,” Stringer said.
Scientists now know that after Homo sapiens first appeared in Africa about 300,000 years ago, it intermingled with a whole range of hominins, explained Rick Potts, director of the Smithsonian Institution’s Human Origins Program.
Neanderthals got stuck in Europe. Homo heidelbergensis and Homo naledi lived in Africa. The short H. floresiensis, sometimes known as the “hobbit,” lived in Indonesia, while the long-legged H. erectus gravitated toward Asia.
Scientists are beginning to realize that all of these humans were not our direct ancestors. Instead, they were more like our cousins: lineages that branched off from a common source and headed in different directions.
Archaeological finds have shown that some of them had complex behaviors. Neanderthals painted cave walls, Homo heidelbergensis hunted large animals like rhinos and hippopotamuses, and some scientists believe even the small-brained Homo naledi buried their dead in South African cave systems. A study last week found that early humans were building wooden structures before Homo sapiens evolved.
The researcher also wondered: If these other types of humans were not so different, would our ancestors have had sexual relations with them?
For some, this combination was difficult to imagine. Many have argued that when Homo sapiens ventured out of Africa, they replaced other groups without interbreeding. Archaeologist John Shea of Stony Brook University in New York said he thought Neanderthals and Homo sapiens were competitors, believing that “if they bumped into each other, they would probably kill each other.”
But DNA revealed other interactions that changed who we are today.
In 2010, Swedish geneticist Svante Pääbo and his team solved a complex puzzle. They were able to piece pieces of ancient DNA together to form a complete Neanderthal genome, a feat long thought impossible, which led to Pääbo receiving a Nobel Prize last year.
This ability to read ancient DNA has revolutionized the field, and is constantly improving.
For example, when scientists applied these techniques to the pinky bone and some massive molars found in a Siberian cave, they found genes that didn’t match anything seen before, said Bence Viola, an anthropologist at the University of Toronto who was part of the research team. The research team that made the discovery. It was a new species of human, now known as… Denisovanwho were the first human cousins identified by their DNA alone.
Armed with Neanderthal and Denisovan genomes, scientists can compare them to humans today and look for matching DNA fragments. And when they did, They found clear signs of crossing.
DNA evidence showed that Homo sapiens interbred with groups that included Neanderthals and Denisovans. They have even uncovered evidence of other “ghost groups,” groups that are part of our genetic code, but whose fossils we have yet to find.
It is difficult to determine exactly when and where these interactions occurred. It appears that our ancestors mixed with Neanderthals shortly after they left Africa for Europe. They likely encountered the Denisovans in parts of East and Southeast Asia.
“They didn’t have a map, and they didn’t know where they were going,” said the Smithsonian’s Butts. “But looking over the next hills into the next valley, they encountered groups of people who looked a little different from them, but who were interbreeding and exchanging genes.”
So, while Neanderthals looked different from Homo sapiens, from their large noses to their short limbs, that wasn’t enough to create a “wall” between the two groups, Shea said.
“Maybe they thought these people looked a little different,” Shea said. “His skin color is a little different. Their faces look a little different. But they are great guys. Let’s try to talk to them.”
The idea that modern humans, especially white humans, were the pinnacle of evolution comes from a time of “colonialism and elitism,” said Janet Young, curator of physical anthropology at the Canadian Museum of History.
Created to reflect the vision of a eugenics advocate, the Neanderthal painting has made its way through decades of textbooks and museum exhibits.
Young said the new findings completely change the idea that previously, more ape-like creatures began to stand more upright and became more complex until they culminated in Homo sapiens. In addition to genetic evidence, Other archaeological discoveries have shown that Neanderthals had complex behaviors regarding hunting, cooking, using tools, and even making art.
However, although we now know that our ancient human cousins were like us, and are part of who we are now, the idea of ape-like cavemen has been difficult to dislodge.
Artist John Gorsch tries. He specializes in creating realistic models of ancient humans for display in museums, including the Smithsonian and the American Museum of Natural History, in hopes of helping public perception catch up with science.
Skulls and sculptures appeared on the shelves of his studio earlier this year while he was working on a Neanderthal head, etching bits of hair into silicone skin.
Gorsch said that bringing the new vision to the public was not easy: “This image of the caveman is very persistent.”
For Gorchi, getting the science right is crucial. He has dissected humans and apes to understand their anatomy, but also hopes to highlight emotion in his images.
“These were once living, breathing individuals. They felt sadness, joy and pain,” Gorshi said. “They are not in fantasy land; they are not imaginary creatures. “They were alive.”
Scientists can’t get useful genetic information from every fossil they find, especially if it’s really old or in the wrong climate. They couldn’t collect much ancient DNA from Africa, where Homo sapiens first evolved, because it had deteriorated due to the heat and humidity.
However, many hope that as DNA technology continues to advance, we will be able to go further into the past and obtain ancient genomes from more parts of the world, adding more strokes to our picture of human history.
Because even though we were the only ones to survive, other extinct groups played a major role in our history and present. They are part of a common humanity that connects every person, said Mary Prendergast, an archaeologist at Rice University.
“If you look at the fossil record, the archaeological record, and the genetic record, you see that we have a lot more in common than we do,” he said.
(With information from AP)